A DC-DC converter works as follows: the PMOS transistor on the DC input voltage side and the NMOS transistor on the ground voltage side are alternately switched on and off to generate a DC output voltage. When a relatively small current flows in the load where the output voltage is applied, the mode becomes the “light-load mode”, and both transistors are maintained in the off state, so that the power consumption of the DC-DC converter can be decreased.
However, when the current flowing in the load rises rapidly, it takes time to reset the mode from the light-load mode to the normal operational mode, and during this period the output voltage falls significantly, which is undesirable.